Structural element



Oct. 29, 1963 G. M. ADlE STRUCTURAL ELEMENT 2 Sheets-Sheet 1 Filed April'7. 1960 Oct. 29, 1963 G. M. ADlE STRUCTURAL ELEMENT 2 Sheets-Sheet 2Filed April 7. 1960 '1 I lnve flor C K B W W ttarneys United StatesPatent 3,1ll8fi24 STRUCTURAL ELEMENT George lt lountford Ailie, '7Carlos Place, London, England: Filed Apr. '7, I966 Ser. No. 26,672Claims priority, appli-catien Great Eritain Apr. 14,1959 '7 illaims.(Cl. 16l127) This invention relates to materials and elements for use inbuilding constructions and the like and is an improvement in ormodification of prior materials or clements consisting of a slab, panel,block or the like of cellular material in which the density of thematerial is graded so as to be a maximum in the neighbourhood of one orboth of its faces and a minimum in the neighbourhood of the oppositeface or the median plane as the case may be. Such prior material orelements have been formed by the juxtaposition of thin sheets ofmouldable material, such as a thermoplastic, lhaving dimples or cupsformed in them, the open sides of the dimples being brought oppositeeach other to provide cells which were spherical in shape. The cellswere so arranged that the density of the material was a maximum in theneighbourhood of both of its faces and a minimum in the neighbourhood ofthe median plane or" the material. Each outer load-bearing face wasbounded by a skin of non-cellular material.

According to the present invention, a cellular slab, panel, block orlike element is formed of a number of juxtaposed sheets having dimplesformed therein of square, circular, hexagonal or other polygonal crosssection. The size of the dimples in the sheets decreases from sheet tosheet away from the median plane of the element or from one of its facesto the other and the sheets are disposed so that the apex of the dimplesin each intermediate sheet being nested with a dimple in an adjacentintermediate sheet and in contact with the apex of the dimples withwhich they are nested, the depth of the dimples in the sheets decreasingin amount by a factor of two from sheet to sheet from one side to theother of the slab, and all of the apices lying substantially within thesame plane.

The dimples may for example be pyramidal or coni cal in shape or somemay be pyramidal and some. conical. The sheets are preferably ofmouldable material such as thermoplastic or thermosetting plastic,metal, such as mild steel or any other suitable substance. One verysuitable material for all the sheets is pressed fibre because of itscheapness, ease of moulding and lightness. When pressed fibre sheets areused throughout the element then two identical centre sheets are used sothat the element is balanced to counteract any variation which may occurdue to the variation in a sheet of pressed fibre of one of its surfacesas compared with the other surface. When pressed fibre, thermoplastic orother suitable material is used for the sheets then they can be rivetedtogether as well as or instead of being stuck with adhesive.

The pyramidal dimples are preferably truncated so that the apices of thedimples in all the sheets are flat surfaces all of the same size subjectto the necessary allowance for the thickness of the sheet material. Thepitch of the pyramidal dimples in the various sheets is preferablydoubled from sheet to sheet from the outermost dimpled sheet where thedensity of the element is to be greatest to the middle sheet or theopposite outermost dimpled sheet where the density is to be least. Theword pitc wherever used herein is intended to refer to the distancebetween the apices of the dimples, or in other Words, the number ofdimples occupying a given area. Thus the depth of the pyramids in anyrelatively outer sheet is approximately half that of the depth of thepyramids in the next relatively inner sheet. This leads to theproduction of an element having a system of voids constituting atwo-dimensional rectangular or triangular grid of which the grid linesare channels of triangular cross section.

Embodiments of the invention are illustrated in the drawing accompanyingthe provisional specification in which:

FIGURE 1 is an exploded view showing nine sheets which can be assembledtogether to make an element of which FIGURE 2 is a cross sectional view,and in the accompanying drawing in which:

FIGURE 3 is an isometric view of a modified centre sheet, and

FIGURE 4 is a section of a part of a slab incorporating the centre sheetshown in FIGURE 3.

The element shown in FIGURES l and 2 comprises a centre sheet ill, threeintermediate sheets .12, 13 and 14 on each side of the centre sheet andan outer slain or sheet 15 which forms a flat face on each side of theelement. The centre and each of the intermediate sheets is formed with aseries of dimples in the form of hollow truncated pyramids.

The centre sheet 10 is formed with two series of identical pyramidaldimples 16 extending in opposite directions so that the bases of thepyramids occupy the whole of the projected area of the sheet.

Each of the two intermediate sheets 1-2 which are identical is dimpledwith identical truncated pyramids 18 which, however, extend all in thesame direction from the sheet. The pitch of the dimples 18 is half thatof the dimples 16 on one side of the centre sheet 1G and their basesoccupy the whole of the projected area of the sheet. The next pair ofintermediate sheets 13 are also dimpled, the pitch of the dimples 20 inthem being one half of that of the dimples 18. The sheets 14 are formedwith still smaller dimples 22 at one half the pitch of the dimples 20.

The flat surface at the truncated apex of each pyramidal dimple is thesame size and shape for each pyramid on each sheet allowing, of course,for the thickness of the sheet material and the slope of the sides ofeach pyramid is the same so that they can be fitted together one overthe other.

The outermost sheets 15 shown in FIGURE 1 are plane.

The nine sheets shown in FIGURE 1 can be assembled to produce a slabhaving the cross section shown in FIG- URE 2. Alternate pyramidaldimples in the sheets 12 are engaged over the apices of the pyramidaldimples extending to one side or the other of the centre sheet 163;alternate dimples in the sheets 13 are engaged over the apices of thedimples in the sheets 12, alternate dimples in the sheets 14 are engagedover the apices of the dimples in the sheets 13, and the plane sheets 15lie in contact with the apices of the dimples of the sheet 14. It

will be clear from an inspection of FIGURE 2 that the density of thematerial forming the element shown therein is greatest in the region ofthe outside and decreases progressively towards the inside so thatmaterial can be saved and the slab have a high strength to weight ratio.By sticking or welding the sheets together where they are in contactwith each other, a block will be formed which will be of extremely lightweight, which will be highly resistant to penetration and which willhave a good load bearing capacity even though the load is applied overonly a small area.

The truncation of the pyramidal dimples is advantageous as itfacilitates construction of the dimpled sheets and also in the case ofthe outermost dimpled sheet which receives the finishing skin provides agood area of contact between the dimples and the outer skin.

A cross section taken at right angles to that shown in FIGURE 2 will beidentical with FIGURE 2. Therefore, the system of voids defined by thesheets will consist of (i) two series of passages of approximatelytriangular section B, C, D, intersecting each other at right angles andforming two-dimensional grids, '(ii) the hollow interiors E, F, G of thealternate pyramidal dimples 18, 20, 22, and (iii) the interior A and Hof dimples 16.

The intermediate sheets 12, 13 and 14 serve to reinforce not only theouter portions of the element but also the sloping sides of the centresheet and enable the element to withstand highly concentrated loads atpoints along its length. Such an element may be weakest at its medianplane where there is only one thickness of material to resist the loadand therefore it may be advantageous to use a central sheet 10 of amaterial more highly resistant or stronger than adjacent sheets or toprovide a double centre sheet. For example, the centre sheet may be ofsteel while the outer sheets of the composite element could be ofthermoplastic material. Owing to the thickness of the material of thesheets a small web equal in width to the sheet thickness is left betweenthe dimples. Thus the sheets in each side of the central sheet are notin line and the centre sheet is subjected to shear force when the slab'is loaded. In order to minimize this shear force the centre sheet orsheets may be formed with a dog leg, Where it passes between the dimplesin the sheets on each side of it. The dog leg has a width equal to thatof the webs between the dimples or in other words equal to the thicknessof the material. Thus the webs of the dimples in the sheet on one sideof the centre sheet lie immediately in line with the corresponding websin the sheet on the other side of the centre sheet, separated only bythe dog leg portion of the centre sheet. In this way stresses aretransmitted from one sheet to the other without subjecting the centresheet to any substantial shear force.

An example of a slab incorporating such a dog legged centre sheet isshown in FIGURE 4. This figure shows the width of the webs 30, 32between the dimples 18 of the sheets much exaggereated to show theconstruction clearly. In fact the width and that of the dog leg 34 isonly equal to that of the thickness of the material of the sheet. Thesmall webs between the dimples of one sheet lie immediately above thecorresponding webs 32 between the dimples of the sheet on the other sideof the centre sheet the webs 30, 32 being separated only by the dog legportion 34 of the centre sheet. When the webs 30, 32 and dog leg portion34 of the centre have their correct widths, equal to the thickness ofthe sheets, then the sides of the pyramidal dimples of one sheet will bein line with the sides of the pyramidal dimples of the sheet on theother side of the centre sheet.

Instead of the centre sheet 10 being formed with pyramidal dimples onboth of its faces, two sheets having dimples formed only on one of theirfaces can be secured together with their open faces next to each otherto provide a layer having dimples on each side. The pyramids on onesheet can be either staggered with respect to those on the other sheet,can be opposite them or can be diagonally disposed one to another.Further layers are then built up on the same manner as in the elementsdescribed above.

Alternatively a plane centre sheet may be used or indeed no centre sheetat all. In these cases a series of closed cells will be provided in thecentre of the slab.

If the sheets are made of thermoplastic they will conveniently have athickness of the order of four thousanths of an inch. This results in anelement of very low weight, for example, a square foot of the sevensheet element without the outside sheets as described above and stucktogether weighs approximately 7 ozs. and has a resistance to collapseexceeding a quarter of a ton per square foot.

If it is desired that the element have some particular properties suchfor example as acoustic or insulating properties than a sheet or blanketof material having such a property or properties may be included in theelement. Such a blanket if it is very thin say only a few thousandths ofan inch thick, could be placed between each of any two dimpled sheetsbut if it is of greater thickness then it is preferably placed betweenthe two centre sheets.

The blanket could act as an adhesive, a hardener, a heating element, aheat containing or reflecting element, a weather-proofing orfire-proofing element or as a strengthening sheet. If desired it can bearranged to isolate all the grids of ducts between the dimples on oneside of the central sheet from the grids of ducts between the dimples onthe other side on the central sheet.

I claim:

1. A building slab or element comprising a number of superimposedrelatively thin sheets consisting of spaced outermost sheets and atleast three intermediate sheets, the intermediate sheets having aregular series of truncated dimples formed therein arranged on arectangular grid, said dimples having their sides all disposed at thesame slope, the said sheets being disposed in juxtaposition, the apex ofthe dimples in each said intermediate sheet being nested with a dimplein an adjacent intermediate sheet and in contact with the apex of thedimples with which they are nested, the depth of the dimples in thesheets decreasing in amount by a factor of two from sheet to sheet fromone side to the other of the slab, and all of the apices lyingsubstantially within the same plane.

2. A building element as claimed in claim 1 in which the dimples arepyramidal in shape.

3. A slab comprising a number of relatively thin superimposed sheetsconsisting of spaced outermost sheets and at least three intermediatesheets and including a center sheet, said center sheet being formed withtwo regular series of dimples extending in opposite directions, theother intermediate sheets being formed with only one regular series ofdimples extending in one direction, all of said dimples being arrangedon rectangular grids with their sides all disposed at the same slope andhaving truncated apices, the said sheets being disposed injuxtaposition, the apex of the dimples in each said intermediate sheetbeing nested with a dimple in an adjacent intermediate sheet and incontact with the apex of the dimples with which they are nested, thedepth of the dimples in the sheets decreasing in amount by a factorof'two from sheet to sheet away from the median plane of the slab, allof the apices on one side of the median plane of the slab lyingsubstantially within a single plane, and all of the apices on the otherside of the median plane lying substantially within another singleplane.

4. The slab of claim 3, wherein the truncated apices of the dimples areall substantially of the same size.

5. The slab of claim 3 wherein the distance between the truncated apicesof the dimples in each intermediate sheet is halved from sheet to sheetaway from the median plane of the slab.

6. The slab of claim 3 wherein the bases of the dimples in the centersheet occupy the whole of the area of the center sheet.

7. The slab of claim 3 wherein the center sheet is formed with a dog-legbetween the bases of the oppositely extending dimples.

References Cited in the file of this patent UNITED STATES PATENTS E1113Sept. 4, 1934 M011 Apr. 28, 1931 Williams Aug. 30, 1932 Greulich Aug.10, 1937 10

1. A BUILDING SLAB OR ELEMENT COMPRISING A NUMBER OF SUPERIMPOSEDRELATIVELY THIN SHEETS CONSISTING OF SPACED OUTERMOST SHEETS AND ATLEAST THREE INTERMEDIATE SHEETS, THE INTERMEDIATE SHEETS HAVING AREGULAR SERIES OF TRUNCATED DIMPLES FORMED THEREIN ARRANGED ON ARECTANGULAR GRID, SAID SIMPLES HAVING THEIR SIDES ALL DISPOSED AT THESAME SLOPE, THE SAID SHEETS BEING DISPOSED IN JUXTAPOSITION, THE APEX OFTHE DIMPLES IN EACH SAID INTERMEDIATE SHEET BEING NESTED WITH A DIMPLEIN AN ADJACENT INTERMEDIATE SHEET AND IN CONTACT WITH THE APEX OF THEDIMPLES WITH WHICH THEY ARE NESTED, THE DEPTH OF THE DIMPLES IN THESHEETS DECREASING IN AMOUNT BY A FACTOR OF TWO FROM